The present invention relates to a device with an n-i-p-i-n doping configuration. The invention is also similarly applicable to a p-i-n-i-p configuration but will be described as being applied to the n-i-p-i-n structure, for the sake of brevity.
The n-i-p-i-n device is one that has a thin p-layer about 100 .ANG. formed in an i layer of an n-i-n structure, and is now being emloyed as a high-speed device since it is a device in which mainly majority carriers take part in conduction. Moreover, there has also been recently proposed a three-terminal element utilizing this structure. Further, this device can also be employed as a high sensitivity photo detector with no excess noise and has very wide applications as a very high-gain, high speed photo detector. However, the conventional structure of the type has a defect, such as a large dark current under light irradiation.